Dissertationen zum Thema „Effect of spray paints“

Mechanical parameter characterization of very thin polymer films using digital im- age correlation is performed in this work. At present days DIC is widely used in the construction, food industries, and aviation. Despite advantages when compared to other conventional methods, but users still face difficulties with the analysis of thin polymers like low-density polyethylene (LDPE) and polyethylene terephthalate (PET) thin polymer films. For the application of sprays to obtain the best pattern quality as well as the potential of thin-film material properties tempering from the stochastic pattern paint. This research work will investigate the effect of several spray paints on the material response of thin polymer film. It also shows how to achieve good surface traction, time effect, and the type of spray to be used for DIC analysis. Finally, this research also studies how the width of the specimen affects the wrinkling effect, which is a common phenomenon while testing the thin polymer films and exhibits the appropriate width for reducing wrinkles on thin polymer films.

Coanda-assisted Spray Manipulation (CSM) is a means of modifying the direction of a jet. Previous isothermal static vectoring research is expanded to plasma spray. Two- dimensional Particle Image Velocimetry (PIV) was used to determine the vectoring results for small angles between 5-10°. Suitable parameters were determined for use on a plasma spray gun for small angle vectoring. Three-dimensional PIV was used to determine the elect of high speed rotation on a vectored jet. A 2-piece CSM collar was retrotted to a Praxair SG-100 plasma spray gun that replaced the standard faceplate. Two separate collars were tested: one designed for small vector angles and one for larger vector angles. The small-angle device could modify the trajectory of zirconia powder up to several degrees. Doing so could realign the plasma with the powder, resulting in increased powder temperature and velocity. The large-angle device could vector the plasma jet up to 45°; however the powder did not vector as much. Under large-angle vectoring, the powder velocity and temperature decreased steadily with vector angle. Both devices were tested using a supersonic conguration.

Aujourd’hui, le marché de la peinture automobile est gouverné par une demande pour des couleurs profondes et vives avec effets. Dans le domaine de la peinture automobile, l’exigence est très haute car la couleur est associée à un signe de qualité. Dans une collision classique, différentes parties du véhicule peuvent être endommagées avec généralement une partie de la carrosserie qui est touchée. La partie endommagée doit être réparée, poncée et préparée avant d’être repeinte. Pour réduire les coûts, le carrossier doit préparer une peinture avec un bon contretypage de teinte, et ce aussi vite que possible. Il s’agit donc pour la formulation de la peinture de réparation de reproduire les effets, aussi bien colorés que texturés, à partir de pigments absorbants ou à effets (particules d’aluminium, de nacre …). Il est relativement simple de qualifier les effets colorés à partir des courbes de réflectance puis des coordonnées CIELab. Cependant, la définition de la texture engendrée par les particules à effets est assez complexe et n’est encore qu’à ses prémices, avec des paramètres qui souvent ne correspondant pas aux phénomènes réellement perçus par l’œil humain. Dans le cadre de ce travail de thèse, la mobilisation de connaissances expertes à travers différentes sessions de tri libre et de brainstorming a permis la mise en évidence de descripteurs de texture réellement perceptifs. De plus, la mise en place de métriques de texture conçues à partir de préconisations réellement perceptives, a rendu possible l’obtention de valeurs correspondant à un observateur moyen pour chacun de ces paramètres descripteurs. Ces paramètres ayant été élaborés à partir des observations d‘évaluateurs expérimentés. La transposition de ces vérités terrain en descripteurs physiques de texture a permis l’obtention d’une corrélation entre le perceptible et le mesurable. Dans la procédure développée, l’œil humain a été remplacé par un appareil photo numérique agissant en qualité d’intégrateur tristimulaire d’informations radiométriques. En essayant de reproduire les conditions d’observation lors de la phase d’acquisition d’images, il a été ainsi possible de caractériser les phénomènes de texture par analyse d’image et de les corréler aux valeurs de l’observateur moyen préalablement défini
Nowadays, the automotive coating market is governed by a demand for deep and vibrant colors with effects. In this field, the requirement is very high because the color is associated with a sign of quality. In a typical collision, different parts of the vehicle may be damaged. The damaged part must be repaired, sanded and prepared before being painted. To reduce costs, the body shop must then prepare a paint with a good color matching, and thus as fast as possible. It is therefore necessary for the formulation of the repair coating to reproduce the effects, both colored and textured, from absorbent or effect pigments (aluminum particles, pearlescent materials …) from a characterization of the concerned vehicle coating. It is relatively simple to qualify the colored effects from the reflectance curves and then the CIELab coordinates. However, the description of the texturing effect generated by the distribution of effect particles at the microstructure scale is quite complex. The metrological approach of the perceptive properties is still at its beginnings. The parameters used do not necessarily correspond directly to the phenomena actually perceived by the human eye. As part of this thesis work, the mobilization of expert knowledge through various sessions of free sorting and brainstorming on coated samples made it possible to highlight really perceptive texture descriptors. These descriptors have been the subject of "objective" evaluations by experienced observers. They thus made it possible to associate a quantitative evaluation scale with each descriptor. This stage of the present thesis work allowed the establishment of ground truth data materialized by a set of reference samples representing different ordered levels of a descriptor. These ground truth data were then used to design a set of measurable physical texture descriptors that were directly correlated to perceptual scales constructed in the previous step. In the procedure developed, the human eye has been replaced by a digital camera acting as a tristimulus integrator of radiometric information. The image acquisition phase was a decisive step in the process: it was necessary to reproduce the conditions of evaluation of the properties perceived, recognized and retained during the various stages using expert human observers. It was then possible to characterize the texture phenomena by image analysis and to correlate them with the values of the previously defined mean observer

Dust capture for small coal particles (<2.5µm) can be improved if one takes advantage of electrostatic charges that resides on the surface of coal dust particles and on the surface of water spray droplets used to capture coal dust. Traditional dust capture methods that use water sprays are ineffective in capturing small dust particles since the motion of small dust particles is governed by electrostatic forces. If additives such as ionic surfactants could be added to water that would enhance the surface charge on water spray droplets, dust capture with water sprays could be improved. The results presented show that n-sodium octyl sulfate causes the greatest charge enhancement versus the longer chained n-sodium dodecyl sulfate and n-sodium octadecyl sulfate. This can be explained by considering the factors that lead to droplet charge enhancement. Those factors are the mass of surfactant ions at the droplet surface, and the diffusion rate of the surfactant ions from the bulk droplet to the surface of the droplet. Sodium octyl sulfate will have a faster diffusion rate to the droplet surface because of its relatively short length, and will also maximize the mass balance of surfactant ions at the drop surface.

This thesis studies the influence of internal nozzle flow characteristics over a large spectrum of experimental conditions and diagnostics. Experiments were carried out for two nozzle geometries---cylindrical and conical single hole nozzles---and three different fuels. Two of the fuels are pure components---n-heptane and n-dodecane---while the third fuel consists of a three-component surrogate to better represent the physical and chemical properties of diesel fuel. Measurements include a complete hydraulic characterization consisting of instantaneous injection rate and spray momentum flux measurements; a high-speed visualization of isothermal liquid spray; a high-speed visualization of the evaporative inert spray, imaging liquid and vapor phases simultaneously and finally, a high-speed visualization of the high temperature reactive spray, imaging vapor phase and OH* chemiluminescence for each injection event. All high-temperature diagnostics were performed in a continuous flow test chamber that allows an accurate control on a wide range of thermodynamic conditions (up to 1000 K and 15 MPa). The experimental findings from this work, and the large database obtained (available for download at: http://www.cmt.upv.es/DD01.aspx), could be used to validate CFD models that could help the community understand the fundamental driving mechanisms behind these observations.
En esta tesis se estudia la influencia del flujo interno sobre un amplio espectro de condiciones y diagnósticos experimentales. Se realizaron experimentos para dos geometrías de tobera---toberas cilíndrica y cónica de un único orificio---y tres combustibles. Dos de los combustibles son puros---n-heptano y n-dodecano--- mientras el tercero es un combustible sustituto que consiste en una mezcla de tres componentes que busca representar mejor las propiedades físicas y químicas del diesel. Las medidas incluyen una caracterización hidráulica completa, compuesta por tasa de inyección y cantidad de movimiento instantáneas; una visualización de alta velocidad del chorro líquido isotermo; una visualización de alta velocidad del chorro inerte evaporativo, con captura simultánea de las fases líquida y vapor y, finalmente, una visualización del chorro reactivo a alta temperatura, con captura de la fase vapor y la quimioluminiscencia del radical OH* para cada evento de inyección. Todos los diagnósticos en condiciones de alta temperatura fueron realizados en una maqueta de alta presión y temperatura de flujo constante que permite controlar con precisión un rango amplio de condiciones termodinámicas (hasta 1000 K y 15 MPa). Los resultados experimentales y la gran base de datos obtenida en este trabajo (disponible en: http://www.cmt.upv.es/DD01.aspx), podrían ser utilizados para validar modelos CFD detallados que podrían ayudar a la comunidad científica a entender mejor los mecanismos fundamentales que producen los resultados observados.
Aquesta tesi estudia la influència del flux intern sobre un gran espectre de condicions i diagnòstics experimentals. Es van realitzar experiments per a dos geometries de tovera---toveres ci¿líndrica i cónica amb un únic orifici---i tres combustibles. Dos dels combustibles són purs---n-heptà i n-dodecà--- mentre el tercer combustible consisteix en una mescla de tres components que formen un combustible substitut que busca representar millor les propietats físiques i químiques del dièsel. Les mesures inclouen una caracterització hidràulica completa, composta per taxa d'injecció i quantitat de moviment instantanis; visualització d'alta velocitat del doll líquid isoterme; visualització d'alta velocitat del doll inert evaporatiu, capturant simultàniament les fases líquid i vapor i, finalment, una visualització del doll reactiu a alta temperatura, capturant la fase vapor i la quimioluminiscència del radical OH per a cada esdeveniment d'injecció. Tots els diagnòstics en condicions d'alta temperatura van ser realitzats en una insta¿lació d'alta pressió i temperatura amb flux constant que permet controlar amb precisió un ampli rang de condicions termodinàmiques (fins a 1000 K i 15 MPa). Els resultats experimentals i la gran base de dades obtinguda en aquest treball (disponible a la web en: http://www.cmt.upv.es/dd01.aspx), podrien ser utilitzats per tal de validar models CFD detallats que podrien ajudar a la comunitat científica a entendre millor els mecanismes fonamentals que produeixen aquestes observacions.
Viera Sotillo, JP. (2017). Experimental study of the effect of nozzle geometry on the performance of direct-injection diesel sprays for three different fuels [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/81857
TESIS

Thesis (MPhil)--Stellenbosch University, 2003.
Full text to be digitised and attached to bibliographic record.
ENGLISH ABSTRACT: This assignment is devoted to an in depth analysis of the pro- and the contra-positions in the long-standing and costly debate about the question whether to spray with DDT or not in the fight against malaria. I argue that the dilemma whether or not to spray with DDT is born out of a political agenda, hype, exaggeration and misinformation of the first order. Radical environmentalists appear to insist that DDT is a principal contributor of environmental degradation, and the major cause of death amongst wildlife and humans. Worse still, many Western people seem to be under the impression that mosquitoes cannot cause so much human misery as purported, and that malaria is caused by some kind of plant form of life, or even a virus. The proponents of DDT, on the other hand, appear to be convinced that DDT is a saviour of humankind, and argue that the horrors associated with DDT are exaggerated and baseless, as they are not backed by scientific inquiry. Proponents of DDT also believe that anything that is overused may kill, even ordinary table salt. Inthis assignment, both of these positions are scrutinized. On the basis of an historical overview in Chapter I of the history of the use of DDT, and the emergence of the debate about DDT in the wake of Rachel Carson's Silent Spring (1962), Chapter 2 is devoted to an evaluation of seven basic arguments against the use of DDT, while in Chapter 3 six arguments for the use of DDT are weighed. In Chapter 4 a resolution of the dilemma is proposed in which a case is made for a limited use of DDT only for indoor spraying of huts and houses against malaria mosquitoes until such time as a less dangerous alternative for DDT is found that can be used as effectively in the fight against malaria. As such, this case is informed by the strong moral conviction that we cannot allow poor people of colour to die because of a general ban on the use of DDT. Further research on this ethical debate is encouraged.
AFRIKAANSE OPSOMMING: Hierdie werkstuk is toegespits op 'n in-diepte analise van die pro- en kontra-posisies in die voortslepende, asook duur debat oor die gebruik van DDT al dan nie in die bekamping van Malaria. Ek argumenteer dat die dilemma rondom die vraag of DDT gebruik moet word of nie, aangewakker word deur politieke agendas, sensasie, oordrywing en foutiewe informasie van die eerste orde. Radikale omgewingsgesindes dring oënskynlik daarop aan dat die gebruik van DDT 'n hoof-oorsaak is van die agteruitgang van die omgewing, asook 'n primêre oorsaak van dood onder wild en mense. Erger nog, dit wil voorkom of heelwat Westerse mense onder die indruk is dat muskiete nie werklik soveel menslike lyding kan veroorsaak as wat voorgegee word nie, en dat malaria eerder veroorsaak word deur 'n sekere soort plantvorm van lewe, of selfs deur 'n virus. Die voorstaanders van DDT, aan die ander kant, is klaarblyklik oortuig dat DDT 'n redder van die mensdom is, en argumenteer dat die gruwels wat geassosieer word met DDT 'n grondelose oordrywing is, aangesien dit nie deur wetenskaplike ondersoek gesteun word nie. Voorstaanders van DDT glo verder dat enige stof wat in oormaat gebruik word, die dood kan veroorsaak, selfs gewone tafelsout. In hierdie werkstuk word albei hierdie posisies krities bestudeer en bespreek. Op grond van 'n historiese oorsig in Hoofstuk 1 oor die gebruik van DDT, en die ontstaan van die debat oor DDT na aanleiding van Rachel Carson se Silent Spring (1962), word Hoofstuk: 2 gewy aan 'n evaluasie van sewe basiese argumente teen die gebruik van DDT, terwyl in Hoofstuk 3 ses argumente vir die gebruik van DDT oorweeg word. In Hoofstuk 4 word 'n voorstel gemaak vir die resolusie van die dilemma deur 'n saak uit te maak vir die beperkte gebruik van DDT, nl. slegs vir binneshuise gebruik in hutte en huise teen malaria-muskiete tot tyd en wyl 'n minder gevaarlike alternatief vir DDT gevind word wat net so effektief sal wees in die stryd teen malaria. As sulks word hierdie studie gerugsteun deur die sterk morele oortuiging dat ons nie kan toelaat dat mense van kleur sterf as gevolg van 'n algemene verbod op die gebruik van DDT nie. Verdere navorsing oor hierdie etiese debat word aangemoedig.

Acrylic emulsion paint is one of the most common media employed by 20th century painters. Since early acrylic paintings have begun to require the attention of conservators, scientists are working to characterize the properties of these paints to facilitate conservation efforts. In this study, we report an investigation of the physical and chemical properties of acrylic emulsion paints using single-sided NMR in conjunction with gloss measurements and scanning electron microscopy coupled with energy dispersive spectrometry. Combining the data from these techniques gives insight into pigment-binder interactions and the acrylic curing process, showing that as pigment concentration is increased in paints, the amount of binder adsorbed to pigment particles increases, resulting in films with differing relaxation times. Furthermore, pigments with a larger surface area or smaller particle size will have a greater effect on physical properties as concentration increases. This research emphasizes the efficacy of NMR relaxometry in studying cultural heritage objects, and may prompt further study into the effects of pigment concentration on the curing and conservation of acrylic paint films.

Studies were conducted to evaluate the effect of pre-irrigation media moisture deficit, irrigation application rate, and intermittent irrigation on irrigation efficiency [(amount applied - amount leached) amount applied' 100] of spray stake-irrigated, container-grown plants. In the first experiment, pine bark-filled containers were irrigated to replace moisture deficits of 600, 1200, or 1800 ml. Deficits were returned in single, continuous applications at application rates of 148, 220, and 270 ml/min. Application rate did not affect irrigation efficiency. Efficiency decreased with increased medium moisture deficit. In the second experiment, containers, at 600 ml media moisture deficits, were irrigated with 400 or 600 ml (65% and 100% water replacement, respectively). Irrigation volumes were returned in a single, continuous application or in 100ml applications with 30 min intervals between irrigations (intermittent). Irrigation efficiency was greater with intermittent irrigation, 95 % and 84 % for 400 and 600 ml replacement, respectively, than with continuous irrigation, 84% and 67% for 400 and 600 ml replacement, respectively. When applied intermittently, most water loss from containers occurred after 400 ml were applied. In the third experiment, containers were irrigated with 600 ml (100% water replacement) in 50, 100, or 150 ml applications with 20, 40, or 60 min intelVals between applications. A control was included in which 600 ml was applied in a single, continuous application. Irrigation efficiency increased with decreasing application volume and increasing length of interval between applications. The greatest efficiency (86%) was produced with an irrigation regimen of 50 ml applications with at least 40 min between applications. The control treatment (continuous) produced an irrigation efficiency of 62%. When applied intermittently, most water loss from containers occurred after a total of 300 ml were applied.

Master of Science

Thesis (Ph. D.)--West Virginia University, 2007.
Title from document title page. Document formatted into pages; contains xv, 136 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 100-105).

Des revêtements anticorrosion de zinc et d'aluminium ont été développés respectivement par des techniques de pulvérisation à froid à haute pression et à basse pression. Pour les revêtements de zinc, la dépendance de la température de pulvérisation sur l'épaisseur a été analysée et la température critique de dépôt a été trouvée à 230°C. Des variations de pression de 2 MPa, 2,5 MPa et 3 MPa à température constante 290 °C ont montré la valeur d'épaisseur de couche plus élevée à 2 MPa. Il a été également confirmé que l'épaisseur du revêtement à tendance à diminuer avec la pression. Le taux d'alimentation en poudre ainsi que la distance de pulvérisation ont également été considérés comme des paramètres influençant l'épaisseur. Les conditions optimales de projection ont été trouvées pour 3 rps et 30 mm, respectivement. Enfin, la température et la pression du gaz ont été optimisées par le plan d’experience dit de Doehlert. Leurs influences sur la qualité du revêtement de zinc ont été discutées en termes de microstructure, de porosité, d'épaisseur et de résistance à la corrosion. Une porosité maximale de 4,2% a été atteinte avec la pression la plus élevée et avec une température modérée (260 ° C < T < 300 ° C). Ces conditions favorisait l'érosion du substrat et la faible déformation des particules lors de l'impact. Deux conditions optimales ont ainsi été trouvées: 320 ° C – 2,5 MPa et 260 ° C – 2,5 MPa. Des expériences électrochimiques macroscopiques et locales ont été ensuite réalisées. Une résistance à la corrosion plus élevée a été détectée pour la condition 320 ° C – 2,5 MPa. Les revêtements étaient alors suffisamment épais pour protéger le substrat et le mécanisme de corrosion était liée au comportement des couches d'hydroxyde et d'oxyde de Zn. Il est a noter que la rugosité du revêtement devra être pour réduire l'amorçage de la corrosion. Pour les revêtements d'aluminium, les paramètres de déposition optimaux ont été trouvés à 400 ° C / 0,65 MPa. Des particules de céramique ont été ajoutées pour densifier le revêtement permettant une réduction de porosité de 8% à 6,4%. Un traitement de surface par laser a été ensuite effectué. Dans ce travail, la puissance du laser s’est révelée insuffisante pour atteindre le point de fusion de l’aluminium, cependant, la dureté des revêtement a pu être modifée. Les résultats ont montré une augmentation de la microdureté des revêtements de 5% avec l'ajout de particules céramiques tandis qu’une réduction de dureté de 39% et 35% a été mesurée sur le revêtement en aluminium pur et composite respecitvement. La diminution de dureté lors le traitement au laser a été attribuée au recuit de surface, à la libération de contraintes internes et à une possible recristallisation locale. Enfin, les caractérisations électrochimiques ont montré une résistance à la corrosion plus élevée pour les revêtements composites céramiques que l'aluminium pur et les revêtements traités au laser
Anticorrosion coatings of Zinc and Aluminium were developed by high pressure and low-pressure Cold Spray techniques, respectively. For Zinc coatings, the dependence of spraying temperature on thickness has been analyzed and the critical temperature of deposition was found at 230 oC. For lower temperatures, the coating was considerably thinner. Dependence of thickness on pressure variation 2 MPa, 2,5 MPa and 3 MPa at constant temperature 290 oC has shown the highest thickness value at 2 MPa. It was confirmed that the coating thickness tends to decrease with the pressure rise. The powder feeding rate as well as the spraying distance were also considered to influence the thickness. The optimal conditions were found for 3ps and 30 mm, respectively. Finally, the gas temperature and pressure were optimized by a Doehlert uniform shell design. Their influences on the zinc coating quality were discussed in terms of microstructure, porosity, thickness, and corrosion resistance. A maximum porosity of 4.2% was reached with the highest pressure and with a moderate temperature (260 °C < T < 300 °C). These conditions promoted erosion of the substrate and a lower accommodation of particles at the impact. Thicker coatings were obtained at higher temperatures because of better particle straining. Two optimal conditions were then identified: 320 °C–2.5 MPa and 260 °C–2.5 MPa. Macroscopic and local electrochemical experiments were performed. Higher corrosion resistance was detected for the condition 320 °C–2.5 MPa. Coatings were enough thick to protect the substrate and the corrosion mechanism was driven by the classical Zn hydroxide and oxide layers. Note that the coating roughness may be optimized later to reduce the corrosion initiation. For aluminum coatings deposited by a low-pressure cold spray method, the optimal spraying parameters according to deposition efficiency were found at 400 °C /0.65 MPa. Ceramic particles were added to densify the coating and allowed to reduce porosity from 8% to 6.4%. Instead of ceramic particle addition, laser surface treatment was performed after coating design. Laser power was not enough high to reach the surface melting, however, the coating microhardness was modified. Results showed a microhardness increase of coatings of 5% with the addition of hard particles whereas the microhardness decreased after the post-heat treatment (pure aluminum coating reduction of 39% and for composite coating 35%). The hardness reduction during the laser treatment was attributed to surface annealing and the release of internal stresses and possible recrystallization with the subsequent grain growth. Finally, the results of the electrochemical investigations showed higher corrosion resistance of ceramic composite coatings than both pure aluminum and laser-treated coatings

[ES] En los últimos años, la evolución de las tecnologías de inyección ha permitido no solo mejorar el proceso de mezcla, sino también controlar con precisión los parámetros de inyección, agregando flexibilidad a los sistemas para nuevas estrategias y un grado adicional de complejidad para los investigadores. Más aún, las estrategias de inyecciones múltiples han demostrado ser capaces de reducir el consumo de combustible, así como también la emisión de partículas, los óxidos de carbono, los óxidos de nitrógeno, el hollín y los hidrocarburos no quemados, convirtiéndose en un estándar en la industria. Esta tesis presenta una metodología experimental para estudiar los efectos de dos estrategias diferentes de inyección múltiple (piloto-principal y principal-post) sobre el desarrollo fundamental y la combustión del chorro. Primero, se caracterizó hidráulicamente el inyector midiendo su tasa de inyección y flujo de cantidad de movimiento. Para una masa inyectada objetivo, se obtuvo la distribución de combustible para los diferentes tiempos de separación y las cantidades de piloto/post. Se implementó un nuevo enfoque para evaluar la distribución de combustible utilizando la señal de flujo de cantidad de movimiento. Se pudo observar que las inyecciones de piloto/post que se realizan en un estado totalmente transitorio presentan mayor desviación entre disparos. El aumento de la cantidad inyectada redujo la dispersión, con un ligero descenso al disminuir también la presión del rail. La repetibilidad de las inyecciones post se vio afectada significativamente por el tiempo de separación entre pulsos. Luego, se aplicaron diagnósticos ópticos de alta velocidad para visualizar el desarrollo del chorro en atmósferas tanto inerte como reactiva. Se utilizaron dos nuevas soluciones de procesado de imágenes: una para desacoplar dos eventos de inyección que coexisten en un solo cuadro, y otra para estimar el tiempo de retraso al autoencendido de múltiples inyecciónes. En cuanto al desarrollo del chorro en condiciones inertes, no se observó ninguna influencia en la longitud líquida estabilizada y el ángulo del chorro, respecto a la cantidad inyectada por la piloto, ni de su separación al pulso principal. Con respecto a la fase vapor, el aumento de la masa inyectada del primer pulso empujó la zona de transición más allá del límite óptico. En general, el segundo pulso penetró a una mayor velocidad, comparado con el caso de una inyección única. El ángulo de dispersión de la fase de vapor aumentó con la inclusión de la inyección piloto, pero no se observó una tendencia clara con respecto a la cantidad de la piloto ni a su tiempo de separación. En cuanto al desarrollo del chorro en condiciones reactivas, el tiempo de retraso al autoencendido del segundo pulso disminuyó en referencia a su inicio de inyección. En promedio, las estrategias piloto-principal vieron reducciones del 30% al 40%, mientras que las principal-post del 40% al 50%. Con respecto a la longitud de despegue estabilizada, no se observó una tendencia definida con respecto a los efectos tanto del tiempo de separación como de la cantidad de la piloto. La imagen promedio tomada por la cámara intensificada no consideró que la longitud de despegue puede cambiar desde el inicio de la combustión hasta el establecimiento de la llama de difusión. En general se observó que las estrategias piloto-principal producen más hollín que cada uno de sus casos de referencia. Se observó una ligera disminución en el grosor óptico de la sección transversal cerca del inicio de la combustión al aumentar la masa de la piloto. No se observó una clara dependencia del hollín con respecto al tiempo de separación entre pulsos. En contraste a la literatura, las estrategias principal-post mostraron una formación de hollín ligeramente más alta (o similar) que una sola inyección. En cámaras de combustión con un volumen tan grande, la post
[CAT] En els últims anys, l'evolució de les tecnologies d'injecció ha permés no només millorar el procés de mescla, sinó també controlar amb precisió els paràmetres d'injecció, afegint flexibilitat als sistemes per a noves estratègies i un grau addicional de complexitat per als investigadors. A més a més, amb les estratègies d'injeccions múltiples s'ha demostrat la possibilitat de reduir el consum de combustible, així com les partícules, els òxids de carboni, els òxids de nitrogen, el sutge i els hidrocarburs no cremats; a més, aquestes estratègies s'han convertit en un estàndard en la indústria. Aquesta tesi estudia els efectes de dues estratègies diferents d'injecció múltiple (pilot-principal i principal-post) sobre el desenvolupament fonamental i la combustió del doll. Primer, es caracteritzar hidràulicament l'injector, mesurant la seua taxa d'injecció i flux de quantitat de moviment. Per a una massa injectada objectiu, es va obtindre la distribució de combustible per als diferents temps de separació i les quantitats de pilot/post. Es va implementar un nou enfocament per tal d'avaluar la distribució de combustible utilitzant el senyal de flux de quantitat de moviment. Es va poder observar que les injeccions de pilot/post injecció que es realitzen en un estat totalment transitori presenten major desviació entre trets. L'augment de la quantitat injectada va reduir la dispersió, observant un lleuger descens en disminuir també la pressió de rail. La repetitivitat de les injeccions post es va veure afectada significativament pel temps de separació entre polsos. Després, es van aplicar diagnòstics òptics d'alta velocitat per a visual-itzar el desenvolupament del doll en atmosferes tant inerts com reactives. Es van utilitzar dues noves solucions de processament d'imatges: una, per a desacoblar dos esdeveniments d'injecció que coexisteixen en un sol quadre, i una altra per a estimar òpticament el retard a l'encesa amb múltiples polsos d'injecció. Pel que fa al desenvolupament del doll en condicions inerts evaporatives, no es va observar cap influència en la longitud líquida estabilitzada i l'angle del doll respecte a la quantitat injectada per la pilot, ni de la seua separació al pols principal. Pel que fa a la fase de vapor, l'augment de la massa injectada del primer pols va empényer la zona de transició més enllà del límit òptic. En general, el segon pols va penetrar a una velocitat més gran comparat amb el cas d'una injecció única. L'angle de dispersió de la fase de vapor va augmentar amb la inclusió de la injecció pilot, però no es va observar una tendència clara pel que fa a la quantitat de la pilot ni al seu temps de separació. En condicions reactives, el retard d'encesa del segon pols va disminuir en referència a l'inici de la injecció. De mitjana, les estratègies pilot-principal van experimentar reduccions del 30% al 40%, mentre que les principal-post, es van veure reduides entre el 40% i el 50%. Pel que fa a la longitud d'enlairament estabilitzada, no es va observar una tendència definida pel que fa als efectes tant del temps de separació com de la quantitat de la injecció pilot. La imatge mitjana presa per la càmera intensificada no va considerar que la longitud d'enlairament puga canviar des de l'inici de la combustió fins a la flama de difusió establerta. Pel que fa als mesuraments de sutge, en general es va observar que les estratègies pilot-principal van produir més sutge que cadascun dels seus casos de referència. Es va observar una lleugera disminució en el gruix òptic de la secció transversal prop de l'inici de la combustió en augmentar la massa de la injecció pilot. No es va observar una clara dependència del sutge amb el temps de separació entre els pols. En contrast amb la literatura, les estratègies principal-post van mostrar una formació de sutge lleugerament més alta (o similar) que una sola injecció. En cambres amb un volum tan
[EN] In recent years, the evolution of the injection technologies has permitted not only to improve the spray mixing process but to control injection parameters accurately, adding flexibility to the systems for new strategies and an extra degree of complexity for researchers. In such sense, multiple injection strategies have proved capable of reducing fuel consumption, as well as emissions of particulate matter, carbon oxides, nitrogen oxides, soot, and unburned hydrocarbons, and has become a standard in the industry. This thesis provides an experimental methodology to study the effects of two different multiple injection strategies (pilot-main and main-post) on spray development and combustion. Experiments were divided into four separate measurement campaigns carried out in three facilities. In the first two campaigns, the injector was hydraulically characterized by rate of injection and spray momentum flux measurements. For a target injected mass, the fuel allocation was obtained for the different dwell times and pilot/post quantities. A new approach to evaluate the fuel distribution using the momentum flux signal was implemented. Higher shot-to-shot deviations were observed for the pilot/post pulses that are injected in an entirely transitory state. The dispersion decreased with increasing injected quantity, and also slightly with decreasing rail pressure. The repeatability of the post injections was significantly affected by the dwell time. Then, high-speed optical diagnostics were applied to visualize the spray development in both inert and reactive atmospheres. Two novel image processing solutions were developed: one to decoupled two injection events that coexist in a single frame, and another to optically estimate the ignition delay of multiple injection pulses. On the spray development in non-reactive conditions, no influence was observed from the injected quantity of the pilot and its dwell time to the main pulse on the stabilized liquid length and spreading angle. Regarding the vapor phase, increasing the injected mass of the first pulse pushed the interaction zone past the optical limit. In general, the second pulse penetrated at a faster rate than the single injection case. Vapor phase spreading angle increased with the inclusion of a pilot injection. No clear trend was observed with either the pilot quantity nor the dwell time. On the spray development in reactive conditions, for all test points that included multiple injections, the ignition delay of the second pulse decreased referenced to its start of injection. On average, pilot-main strategies showed reductions of 30% to 40%, while main-post of 40% to 50%. Different inter-action mechanism found in the literature were used to describe the synergy between injection pulses. Regarding the stabilized lift-off length, no definite trend was observed in terms of the effects of both the dwell time and pilot quantity. The average image taken by the ICCD camera did not consider that the lift-off length can change from the inception of combustion to the established diffusion flame. Regarding soot measurements, it was generally observed that pilot-main strategies produced more soot than each of their reference case. A slight decrease in the cross-sectional optical thickness near the start of combustion was noted increasing the pilot quantity. No clear dependence of soot on the dwell time was observed. In contrast to the literature, main-post strategies depicted slightly higher (or similar) soot formation than a single injection. In combustion chambers with such large volume, the post injection behaved like a main and the actual main like a pilot. Thus, local conditions enhance the formation of soot from the post injection, instead of promoting its oxidation. Therefore, jet-wall interactions are critical for the effectiveness of the post injection on reducing soot emissions.
Viera Sotillo, AA. (2019). Effect of multiple injection strategies on the Diesel spray formation and combustion using optical diagnostics [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/123954
TESIS

Fuel direct injection represents one of the key turning points in the development of the Diesel engines. The appeal of this solution has been growing thanks to the parallel advancement in the technology of the injection hardware and in the knowledge of the physics involved in the spray formation and combustion. In the present thesis, the effect of partial needle lift and injection rate shaping has been investigated experimentally using a multi-orifice Diesel injector. Injection rate shaping is one of the most attractive alternatives to multiple injection strategies but its implementation has been for long time impeded by technological limitations. A novel direct-acting injector prototype made it possible to carry out the present research: this injector features a mechanical coupling between the nozzle needle and the piezo-stack actuator, allowing a fully flexible control on the nozzle needle movement and enabling partial needle lift as well as the implementation of alternative injection rate shapes typologies. Different optical diagnostics were applied to study the spray development and combustion in a novel continuous flow test chamber that allows an accurate control on a wide range of thermodynamic conditions (up to 1000K and 15MPa). In addition, hydraulic characterization tests were carried out to analyze the fuel flow through the injector nozzle. Partial needle lift has been found to affect the injection event, reducing the mass flow rate (as expected) but also causing a reduction in the effective orifice area and an increase on the spreading angle. Moreover, at this condition, higher hole-to-hole dispersion and flow instabilities were detected. Needle vibrations caused by the needle interactions with fuel flow and by the onset of cavitation in the needle seat are likely the causes of this behavior. Injection rate shaping has a substantial impact on the premixed phase of the combustion and on the location where the ignition takes place. Furthermore, the results proved that the modifications in the internal flow caused by the partial needle lift are reflected on the ignition timing. On the other hand, the analysis of the experimental data through a 1D spray model revealed that an increasing mass flow rate (e.g. ramp or boot injection rate profiles) causes an increase in the fuelair equivalence ratio at the lift-off length and a consequent higher soot formation during the diffusive phase of the combustion. Finally, the wide range of boundary conditions tested in all the experiments served to draw general conclusions about the physics involved in the injection/combustion event and, in some cases, to obtain statistical correlations.
Bardi, M. (2014). PARTIAL NEEDLE LIFT AND INJECTION RATE SHAPE EFFECT ON THE FORMATION AND COMBUSTION OF THE DIESEL SPRAY [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/37374
TESIS

Thesis (MScIng)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: An investigation was made into the use of pre-cooling of air with evaporative cooling as a means of improving the performance of air-cooled heat exchangers (finned tube) under conditions of ambient temperatures above maximum design values and during times of increased load. A review of previous research on this subject indicated that the concept is theoretically sound, but that practical application thereof is still limited. It was found that one of the major areas of concern is the wetting of the heat exchanger finned surface and subsequent corrosion. Mathematical models were derived for the behavior of liquid droplets in free air stream conditions and droplets that have penetrated a laminar hydrodynamic boundary layer formed on a flat plate. These two models were combined to determine the behavior of a liquid droplet for its entire lifetime. It was found that evaporation of droplets in a boundary layer resulted in major improvements in heat transfer. In an attempt to prevent droplets from impacting and wetting the finned tube heat exchanger, the use of electrostatically charged water spray was investigated. Experiments were performed to determine the charging performance of a capacitive electrostatic nozzle. It was found that this type of nozzle successfully charged droplets in a spray. Experiments were then performed whereby electrostatic spray was sprayed on to a heat exchanger with a similar electric charge as the droplets. It was found that droplet deposition decreased significantly as the charge on the droplets was increased. However, total prevention of deposition could not be achieved, since the equipment used could not produce high enough voltages. This concept shows some promise, and it is recommended that further research be performed on it. At this stage, no reliable method of evaporative precooling of air has yet been found. The only viable option for cooling capacity shortages at present is the construction of large air-cooled heat exchangers or the addition of wet cooling towers.
AFRIKAANSE OPSOMMING: Voorverkoeling van lug deur middel van verdampingsverkoeling vir die gebruik met droë lug-verkoelde vinbuis warmteruilers is ondersoek as ‘n manier om die verkoelingseffektiwiteit te verhoog gedurende tye van hoë omgewingstemperature en verhoogde las. ‘n Ondersoek van navorsing op die gebied het getoon dat die konsep in teorie moontlik is, maar dat daar nog geen praktiese implementering plaasgevind het nie. Dit blyk dat die benatting en korrosie van die vinbuise een van die hoof probleme is. Wiskundige modelle is afgelei vir die gedrag van ‘n water druppel in ‘n vrye lug stroom en vir ‘n druppel in ‘n laminêre hidrodinamiese grenslaag op ‘n plat plaat. Die twee modelle is gekombineer om die gedrag van ‘n druppel gedurende sy totale leeftyd te bepaal. Die model het getoon dat verdamping van ‘n druppel in die grenslaag ‘n drastiese verhoging in die hitteoordrag koëffisiënt veroorsaak. Die gebruik van elektrostaties gelaaide sproei om te verseker dat die vinbuis warmteruiler droog bly is ondersoek. Eksperimente is uitgevoer om die elektriese laaivermoëns van ‘n kapasitiewe elektrostatiese mondstuk te bepaal. Daar is gevind dat die tipe mondstuk suksesvol is in die laai van druppels. Toetse is toe uitgevoer waartydens gelaaide druppels gespuit is op ‘n warmteruiler met dieselfde lading as die druppels. Daar is gevind dat die duppel neerslag op die warmteruiler merkwaardig afneem namate die lading op die druppels verhoog is. Die warmteruiler kon egter nie totaal droog gehou word nie, aangesien die toerusting gebruik vir die toetse nie ‘n hoë genoeg spanning kon gee nie. Hierdie konsep is belowend, en dit word aanbeveel dat verdere navorsing daarop gedoen word. Op hierdie stadium is daar nog geen betroubare metode gevind om die verkoelings effektiwiteit van lugverkoelde warmteruilers met verdampings verkoeling te bewerkstellig nie. Die enigste sinvolle opsie tans is die kostruksie van groter lugverkoelde warmteruilers of die konstruksie van nat koeltorings.

The continuing tightening of emission regulations has encouraged extensive research into fuel spray vaporising and combustion. This thesis is an investigation into the effect that the cylinder boundaries have upon the quantity and composition of the unburnt hydrocarbons present in the exhaust gas and particulate matter. To determine the cylinder boundaries' effect on the exhaust hydrocarbon content a series of engine tests was completed. The engine used for these experiments was a modem four cylinder turbo charged direct injection diesel engine, operated at five steady state test points. The test consisted of two standard engine builds to determine the accuracy of measurement and to supply a base point for comparison. The second test used standard pistons with modified oil control rings to increase the oil film thickness. The final test used pistons with the top ring moved nearer the top of the piston by 5.5 mm to reduce the top land crevice volume by ?55%.The composition of the particulate soluble organic fraction (SOF) for the test using the low tangential load oil control piston ring was shown to have a greater fuel content than for other tests, showing that adsorption of the fuel in the lubricating oil contributes to the particulate. The reduction of the top ring crevice volume produced similar quantities of particulate SOF but it consisted of generally lighter hydrocarbon species. The effects of these changes were replicated in a mathematical model which calculated the in cylinder values for fuel, soot, temperature and hydrocarbons. The model also simulated the oxidation of hydrocarbons at the cylinder boundary and consisted of 3 primary zones; the combustion chamber, crevice volume and oil film. This research shows that careful design of engine components can influence the quantity and composition of the particulates exhaust gas and allow the reduction of regulated components.

Air, nitrogen, argon and carbon dioxide were used as the atomizing gas in an 'air-assist' spray nozzle to determine the effect of these gases on mean droplet size, number density, velocity and their distributions in kerosene fuel spays and spray flames using a two dimensional phase Doppler interferometer. Data have been obtained with these atomizing gases using a base, air assisted case as a reference, since this is the most commonly used atomizing fluid in almost all applications. Comparisons were made between the gases on a mass and momentum flux basis. Both burning and nonburning sprays were investigated. The results show significant differences in atomization characteristics from the atomizer with different gases and under conditions of constant mass and momentum flux of the gas. The results also show that the presence of oxygen in the air atomized sprays assists in the combustion process, since it produces smaller and faster moving droplets, especially at locations near to the nozzle exit. In nonburning sprays, droplets had similar size and velocity. Lighter gases such as nitrogen more effectively atomized the fuel in comparison to the denser gases. Argon and carbon dioxide produced larger, slower moving droplets than air and nitrogen assisted cases in both the burning and nonburning sprays. Flame photographs revealed the argon and carbon dioxide atomized flames to have greater luminosity than air or nitrogen atomized flames.

Master of Science

This study investigates the influence of spray nozzle internal geometry on heat transfer performance and the resultant power requirements. An experimental apparatus was designed and built, which allowed for close control of the heat transfer from air to water and the required energy for droplet production. The apparatus allowed for simultaneous measurements of heat transfer rate from the gas to the spray droplets and the pumping power requirements for the sprayed liquid. A spray chamber was constructed in the form of a Perspex cylinder, 372 mm internal diameter and 372 mm height, mounted on its vertical axis. Thermocouples, humidity sensors, and pressure sensors were used to measure the temperature difference of the air and water, the humidity difference of the air, and the pressure drop across the nozzle. The spray nozzles have been installed at the centre of the upper cover plate directed along the cylinder axis. The heat and mass transfer process was carried out in a counter current flow. Two different nozzle designs were the subject of this investigation. The pressure swirl nozzle works on liquid pressure alone. Droplet formation and size is influenced by changes of the internal geometry and liquid pressure. An effervescent two fluid atomiser with internal mixing was tested. The influence of changes in gas bubble and exit orifice geometry on droplet size and formation was investigated. Analysis of the heat transfer process is based on the energy balance for the whole cylinder. This analysis allows for the determination of the nozzle with the best performance characteristics. From the required energy to produce the droplets and the rate of heat transfer, a new equation for the index of energy performance, was defined. A Laser Doppler Analyser was used to determine the droplet size and velocity for the low pressure nozzles and this data was compared with the existing theory. The droplet distribution of the spray nozzles was determined for various configuration. The measured droplet size was below the calculated droplet size using the derived equations from the literature. Photographs of the spray angle at different liquid pressures were taken for digital analysis. The spray angle showed reasonable agreement with the literature. A three dimensional numerical model was designed to simulate the heat transfer process inside the spray chamber using PHOENICS, a Computational Fluid Dynamics (CFD) software. The software modelled the heat and mass transfer inside the spray chamber. This model then allowed for the testing of different droplet distributions, formations, and their influence on the heat transfer process. In order to validate the results, the necessary variables such as the gas mass flow, liquid mass flow rate, droplet size, spray angle and scatter, hot air inlet temperature, were obtained from the experimental data. The result of the simulation is the air outlet temperature and humidity of the spray chamber. The internal 3D flow field is solved with the Lagrangian and Eulerian equation including the disturbance, solved with the k-epsilon turbulence model, created by the spray droplets. Four different pressure swirl configurations were simulated. Every configuration had five different pressure points. Every pressure point was simulated individually in order to find out if the numerical simulation software was able to predict the correct result for different liquid mass flow rates without altering the boundary setting and parameters. The heat transfer process was found to depend on the droplet size and distribution produced by the spray nozzle. A comparison of the experimental data with the simulation results demonstrated the accuracy of the CFD model. The temperature accuracy was ±5.9% and for the humidity ±12% on average for all simulations. It was found that the heat transfer of the effervescent atomiser depends on the mass ALR and that the highest heat transfer was measured when it was operating with an ALR of 0.1. The tested effervescent atomiser was found to be strongly influenced by the atomising air, an effectiveness of 93% achieved. The change of the internal geometries had no significant influence on the heat transfer rates. The change of the internal geometry, especially the exit orifice diameter, had a strong influence on the pressure swirl nozzle performance, which started at 85% and reached a maximum of 95%. It was found that the pressure requirement for the 4.7 mm exit orifice was only 20% of the pressure requirement of the 2.5 mm exit orifice in order to achieve the same cooling performance. The pressure swirl needed for all flow rates approximately 20 times less energy to achieve the same cooling as the effervescent nozzle.

The objective of the thesis is to understand the particle/substrate interaction of micron-sized High Purity (HP) aluminum (Al) powder particles with varying surface oxide/hydroxide layers, during single particle impact and determine the critical impact velocity (CIV). Advancements in analytical techniques enable in-situ supersonic impact of individual metallic micro-particles on substrates with micro-scale and nanosecond-level resolution. This novel capability allowed direct observation and measurement of a material-dependent threshold velocity, above which the particle underwent impact-induced material ejection and adhered to the substrate, (critical impact velocity). The data was then compared to empirical, as well as predicted values of the CIV from published data that were based upon theoretical iso-entropic fluid dynamics models. A major emphasis of this research was to perform, in-depth characterization of the Al powder in the as-received, gas atomized state and subsequent to controlled temperature and humidity exposure (designed to form a prescribed oxide and/or hydroxide surface layer) and finally after single particle impact. Analytical techniques including XPS, ICP, IGF, TEM and SEM were performed to determine the species of oxide and/or hydroxide, bulk chemical composition, oxygen content and thickness of the surface oxide/hydroxide layer. Finally, bulk samples of material were produced by the cold spray process, from powder representing select test groups and subsequently characterized to determine tensile and hardness properties, chemistry, microstructure and conductivity. A fundamental understanding of the role of surface oxidization in relationship to particle deformation during impact and the bonding mechanism will be applicable toward the development of optimized parameters for the cold spray (CS) process. Results from this study will aid in the development of industrial practices for producing, packaging and storing Al powders.

There is currently considerable interest in new engine technologies to assist in the improvement of fuel economy and the reduction of carbon dioxide emissions from automotive vehicles. Within the current automotive market, legislative and economic forces are requiring automotive manufacturers to produce high performance engines with a reduced environmental impact and lower fuel consumption. To meet these targets, further understanding of the processes involved in in-cylinder combustion is required. This thesis discusses the effect of fuel spray structure, flame propagation and turbulent flow on DISI engine combustion. To investigate these flow processes within the fired single cylinder Jaguar optical engine a number of optical measurement techniques have been used, including high speed laser sheet flow visualisation (HSLSFV) and high speed digital particle image velocimetry (HSDPIV). Results obtained from dual location flame imaging has provided further understanding of the relationship between flame growth, engine performance and cycle-to-cycle variation. Detailed correlation analysis between flame growth speed and engine performance parameters demonstrated that it is the flow conditions local to the spark plug at the time of spark ignition that have greatest influence on combustion. It was also demonstrated that further gains in engine performance and stability can be achieved by optimising the fuel injection timing. The temporal and spatial development of flow field structures within the pent-roof combustion chamber at the time of spark ignition were quantified using HSDPIV. Decomposition analysis of the raw velocity data enabled the relationship between specific scales of turbulent flow structure and engine performance parameters to be investigated. Correlations between the high frequency turbulence component and pressure derivatives are shown, demonstrating that it is the frequencies of motion >600 Hz that have the greatest influence on early flame development and therefore rate of charge consumption, engine performance and combustion stability. A series of double fuel injection strategies were devised to investigate the potential for using the fuel injection event to influence flow field structures within the cylinder. Results demonstrated that while the fuel injection event had limited impact on bulk flow structures, there was an increase in turbulence post fuel injection, depending on the timing of the second injection pulse. However, this advantage was not sustained throughout the compression stroke to have significant impact on combustion. The final stage of research investigated fuel spray structure, flame propagation and charge motion at fuel impingement locations, comparing a single and triple injection strategy. A triple injection strategy is proposed that results in an improvement in the levels of fuel impingement on combustion chamber walls and a reduction in the high luminosity regions within the flame. Consequently, adopting the multiple injection strategy highlighted the potential for reducing unburned HC emissions and soot formation within homogeneous charge DISI engines.

Direct Injection Spark Ignition has become popular within the automotive industry due to the flexibility in injection strategies. This, along with the introduction of novel fuels such as mixtures of ethanol or butanol with gasoline, requires new understanding of the air-fuel mixture preparation and combustion as fuel properties vary greatly. The motored engine flow field of an optical research engine was characterised using Laser Doppler Velocimetry and Particle Image Velocimetry and analysed regarding turbulence properties at the world wide mapping point. The intake flow effect on the spray of a pressure swirl injector was investigated using the base fuels gasoline, isooctane, ethanol and butanol. Furthermore, low percentage splash blended mixtures of 25 % ethanol and 16 % or 25 % butanol with the reference fuels were created and geometrical spray features were obtained from high speed imaging along with the droplet sizes using Phase Doppler Anemometry. Spray investigations were also under taken in a quiescent environment with a more modern spark eroded multi hole injector and its direct replacement featuring a novel Laser drilled nozzle. The results highlight the strong effect of the fuel type, where especially pure butanol showed largest difference to the baseline fuels in terms of shape along with a significant increase of the droplet size. Ethanol also showed an increase in droplet size but only small differences to gasoline’s spray shape at 80 bar or 120 bar fuel pressure into 0.5 bar or 1 bar ambient air at 20 °C, for fuel temperatures of 20 °C or 80 °C. The ethanol mixture was typically more similar to gasoline than the butanol blends. Thermodynamic parameters were derived using incylinder pressure analysis for stoichiometric (λ=1) and lean (λ=1.2). Additionally, high speed chemiluminescence imaging was used at gasoline’s maximum break torque spark timing, calculating flame radii, radius growth, roundness and centroid development. Further analysis was using flame tomography for better insight into the early stages after ignition and the flame front characteristics for the base fuels only. Overall, the analysis showed little difference between gasoline and the blends, but showed changes for the pure alcohols with typically much faster flame progression of ethanol and issues with the combustion of butanol at low engine temperatures. The tomography analysis returned similar flame structures for the pure fuels, what is confirmed by their location in combustion diagrams.

PIX was applied to long and short staple cotton in 5, 10 and 20 gallons of water in an incomplete factorial design involving 0.5, 1 and 2 pints of the product per acre. Plant heights were significantly shortened and the percent of lint obtained in the first picking was significantly increased when Piz was applied on the short staple cotton. No statistically significant yield differences were observed between the volumes of dilution or the rates of application for either long or short staple cotton. A factor underlying the experiment was that the monsoon rains. They kept the surface of the ground moist and the plants looking good; however, the subsurface moisture had apparently been depleted, and the plants were under some stress. This stressed condition offset what good the FIX might have done for yield.

Thesis (Ph. D.)--Ohio State University, 2003.
Title from first page of PDF file. Document formatted into pages; contains xxii, 303 p.: ill. (some col.). Includes abstract and vita. Advisors: H. Erdal Ozkan and Richard C. Derksen, Dept. of Food, Agricultural, and Biological Engineering. Includes bibliographical references (p. 213-221).

La Crosse virus (LACV) encephalitis is the most common and important endemic mosquito-borne disease of children in the U.S. with an estimated 300,000 annual infections. The disease is maintained in a zoonotic cycle involving the eastern treehole mosquito, Aedes triseriatus and small woodland mammals such as chipmunks and squirrels. The objectives of this study were 1) to conduct surveillance of LACV and other mosquito-borne viruses; 2) to evaluate the effect of virus infection on mosquito host-seeking and neurotransmitter levels, and 3) to determine the effectiveness of barrier sprays to control infected mosquito vectors. Our surveillance study demonstrated the involvement of an invasive species, Aedes japonicus, in the transmission cycle of Cache Valley virus (CVV). CVV is a mosquito-borne virus that is closely related to LACV. Thus, surveillance is a critical step in public health, providing pathogen distribution and frequency data as well as identifying and incriminating new vectors. LACV infection did not affect the host-seeking behavior of Ae. triseriatus females. Using high performance liquid chromatography with electrochemical detection (HPLC-ED), the levels of serotonin and dopamine were measured in infected and uninfected mosquitoes. Serotonin is known to affect blood-feeding and dopamine affects host-seeking. Serotonin levels were significantly lower in LACV-infected mosquitoes but dopamine levels were unaffected by virus. A previous study found that LACV infection caused an alteration in mosquito blood-feeding in a way that could enhance virus transmission. This work showed that LACV infection can reduce the level of serotonin in the mosquito, promoting virus transmission through altered blood-feeding without impairing the vector's ability to locate a host. Standard CDC bottle assays were used to evaluate the efficacy of two pyrethroids and two essential oil sprays on LACV infected and uninfected mosquitoes. LACV-infected Ae. triseriatus females were more susceptible to both pyrethroids than uninfected ones. Infection status did not affect the susceptibility of Ae. albopictus to either pyrethroid. The essential oils were inconsistent in their effects. These results demonstrate that barrier sprays may be a viable part of a mosquito control program, not just to reduce the biting rate but to potentially reduce the virus-infected portion of the vector population.
Ph. D.

State of the art thermal barrier coatings (TBCs) for gas turbine applications comprise (7 wt.%) yttria partially stabilized zirconia (7YSZ). 7YSZ offers a range of attractive functional properties – low thermal conductivity, high thermal expansion coefficient and high in-plane strain tolerance. However, as turbine entry temperatures are raised, the performance of 7YSZ coatings will be increasingly affected by sintering and environmental contamination, by calcia-magnesia-alumina-silica (CMAS) deposits. The effect of sintering-induced stiffening on the driving force for spallation of plasma-sprayed (PS) TBCs was investigated. Spallation lifetimes of TBC specimens sprayed onto alumina substrates were measured. A simple fracture mechanics approach was employed in order to deduce a value for the strain energy release rate. The critical strain energy release rate was found to be constant, and if this value had been known beforehand, then the rationale presented here could be used for prediction of coating lifetime. The effect of vermiculite (VM) and volcanic ash (VA) contamination on the sintering-induced spallation lifetime of PS TBCs was also investigated. The presence of both VM and VA was found to accelerate the rise in their Young’s modulus with sintering. Spallation results show that coating lifetime may be significantly reduced, even at relative low addition levels, due to the loss of strain tolerance caused by the penetration of glassy deposits. This result gives a clear insight into the role CMAS plays in destabilizing TBCs. Finally, the adhesion characteristics of ingested volcanic ash were studied using a small jet engine. The effects of engine speed and particle size were investigated. Deposition on turbine surfaces was assessed using a borescope. Deposition mainly occurred on the nozzle guide vane and blade platform. A numerical model was used to predict particle acceleration and heating in flight. It was observed that larger particles are more likely to adhere because they have greater inertia, and thus are more likely to impact surfaces. The temperature of the larger particles at the end of its flight was predicted to be below its softening point. However, since the component surface temperatures are expected to be hotter, adhesion of such particles is probable, by softening/melting straight after impact.

In the past few years, the solution-processed organic based solar cells gained more importance by meeting the demands for cost effective photovoltaic devices. To date, the focus of the organic photovoltaic devices has been on the optimization of the processing the materials to improve photo conversion efficiency and also by modifying the active components of the organic materials. Recently, it has been recognized that the deposition techniques also plays a major role in enhancing the power conversion efficiencies. Currently, though the most common deposition technique for organic solar cells is spin coating, which does not allow scaling up of the large device area. As an alternative method, a simple airbrush spray deposition technique has been developed to fabricate the test devices. The film thickness of the layers was characterized under scanning electron microscope. Devices with different thickness (1000 nm, 500 nm, 240 nm) of poly(3,4-ethylenedioxythipohene) polystyrene sulfonate (PEDOT.PSS) and active layers are prepared and their photovoltaic performances have been evaluated and compared by plotting the IV curves with respect to each thickness. Maintaining the distance between the substrate and the airbrush nozzle the thickness of the layers was controlled. From the results, we found that the test devices with 500 nm thickness of PEDOT.PSS and active layers shows the best device performance with highest current density of 3.97 mA/cm2, open circuit voltage of 1.3 V and power conversion efficiency of 2.34%. As a control experiment, devices were also developed using the standard poly(3- hexylthiophene-2,5-diyl):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) system, but the power conversion efficiencies of these devices were not promising with respect to the literature results. Future studies of this project will focus on improving the power conversion efficiency of poly(3-hexylthiophene-2,5-diyl)/perylenediimide bridged system (P3HT/PDIB) by developing a new device architecture called “tandem solar cells” which consists of multiple layers of different donor and acceptor blends with inorganic transition metal oxides such as zinc oxide and molybdenum oxides.

Objectives: The purpose of this randomized controlled experimental study was to examine how the xerostomia products Biotene® Oralbalance moisturizing liquid and MouthKote® oral moisturizer spray influence mineral content of human enamel in vitro. Methods: 104 caries free extracted human teeth were selected and prepared, followed by baseline QLF imaging and exposure to an erosive solution of lactic acid (pH of 4.5) and/or Biotene®, MouthKote®, as well as Oral-B fluoridated rinse. Mineral loss was determined with respect to mean fluorescence loss (ΔF, %), maximum fluorescence loss (ΔQ, %), and lesion area (WS, %/mm²). Within-group and among-group comparisons were made employing independent sample t-tests, paired sample t-tests, and ANOVA for multiple comparisons with Bonferroni post hoc adjustment, or their non-parametric equivalents. For all tests, the threshold for the statistical significance was set at P < 0.05. The statistical software SPSS 17.0 was used for data analyses. Results: The xerostomia products induced significant demineralization in extracted human teeth with prior demineralization (P=0.000) and without previous pre-demineralization (P = 0.000). There were substantial and statistically significant differences in mineral loss among all groups. The amount of demineralization (Mean ± SD) was higher in MouthKote® group 2 (-27.19 ± 6.70) and group 4 (-11.45 ± 2.94) than in Biotene group 1 (-11.15 ± 3.05) and group 3 (-7.38 ± 0.44) respectively. Oral-B fluoridated rinse aided in re-mineralization, albeit not to baseline levels. Conclusions: Biotene® and MouthKote® induced substantial mineral loss in pre-demineralized and unaltered enamel of extracted human teeth. MouthKote® induced greater demineralization than Biotene®. Oral-B rinse induced re-mineralization in all experimental groups except for group 2 (lactic acid/MouthKote®) where further dissolution of enamel was observed.

The physicochemical properties of a drug affect to a large extent its subsequent biological absorption and bioavailability profile. Considerable pharmaceutical interest is therefore directed torwards the improvement of drug dissolution characteristics of drugs with low aqueous solubility. This thesis has considered the controlled modification of drug dissolution profiles by means of incorporating low concentrations of hydrophilic polymers by different processes into a host drug substance. In order to examine this approach and its potential use, the physicochemical, solid state, stability and tableting properties of a poorly aqueous soluble drug, phenylbutazone, in alternative polymorphic form and containing low levels of two hydrophilic polymers - hydroxypropyl methylcellulose (H.P.M.C.) and the surfactant poloxamer 188 - prepared by both conventional crystallisation and spray drying are reported. As an integral nart of the work attempts were mado to identify the different polymorphic forms of phenylbutazone. The δ-form, the commercially available stable form and the α and β metastable forms (nomenclature after Muller, 1978) were isolated. The α form was found to be unstable on storage. A 2 fold increase in intrinsic dissolution rate was observed for the metastable β-polymorph compared with the stable δ-polymorphic form. The effect of crystallisation rate on the formation of polymorphs of phenylbutazone was studied using a mini-spray dryer, and slower rates of crystallisation were found to favour polymorph formation. The hydrophilic polymers, H.P.M.C. and poloxamer 188, were incorporated by conventional crystallisation and spray drying into the drug crystal. Samples were subjected to a series of tests including differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, and intrinsic dissolution and solubility. When prepared by conventional crystallisation H.P.M.C. was found to form a "high energy" complex with phenylbutazone which melted 10°C lower than the parent drug. When prepared by spray drying H.P.M.C. inhibited the formation of the metastable β-polymorph of phenylbutazone. A 2 fold increase in intrinsic dissolution rate was observed for crystallised and spray dried samples containing 2% w/w or more added polymer. Poloxamer 188 did not form a complex with phenylbutazone and unlike H.P.M.C. did not inhibit the formation of the β-polymorph. For both crystallised and spray dried samples a 3 fold increase in dissolution rate was obtained at polymer levels of 1% w/w or above. The increase in dissolution has been attributed to facilitated wetting by lowering of interfacial tension rather than through the formation of micelles. The stability of selected phenylbutazone:polymer samples was tested at elevated temperatures. The stability was found to be affected both by the method of sample preparation and the type of additive. Large breakdowns occurring by a hydrolytic effect were identified for the crystallised phenylbutazone samples containing poloxamer 188. The effects on compaction of phenylbutazone in alternative form and presence of polymeric additives were studied by compressing samples of similar particle sizes of phenylbutazone as supplied (δ-form), samples of spray dried phenylbutazone (β-form) and samples containing different concentrations of H.P.M.C. prepared both by conventional crystallisation and spray drying. Compaction data were analysed according to the Heckel relationship and by force transmission ratio as well as from the tensile strengths of prepared tablets. The presence of H.P.M.C. up to 5% w/w concentration in phenylbutazone did not change the mean yield pressure for the crystallised or spray dried samples, although a difference in mean value was observed between the crystallised and spray dried materials, 93.22 MPa and 147.02 MPa respectively. Force transmission was found to be improved for samples containing H.P.M.C. prepared by both techniques and in general, the tablet tensile strengths for crystallised samples containing H.P.M.C. were approximately three times greater than for spray dried samples at equivalent tablet porosity. Differences are attributed to variation in solid state and particulate properties between samples.

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O objetivo deste trabalho foi desenvolver um modelo matemático que permita avaliar termodinamicamente equipamentos de secagem, por meio de balanço de massa e energia, elaborar diferentes compostos lácteos a partir da mistura de leite/soro, e avaliar o efeito de compostos de alta massa molar nas propriedades físico-químicas e de secabilidade de compostos lácteos tradicionais e sem lactose. Para a caracterização termodinâmica foi utilizado um spray dryer com atomizador de bico de pressão com capacidade de evaporação de 1 kg de água/hora (SD1) e um spray dryer com atomizador de disco, (com capacidade de secagem de 20 kg de água/hora (SD2). Para a elaboração dos compostos lácteos, foram utilizadas bases lácteas, deslactosadas ou não, elaboradas a partir de diferentes proporções de leite e soro, além de maltodextrinas 10 e 20 DE, inulina e fibra solúvel de milho. O modelo matemático foi válido para avaliação de perdas de massa e energia e permitiu comparar a eficiência entre secadores por aspersão com diferentes desenhos. O aumento no teor de soro nos compostos lácteos e principalmente a aplicação do processo de hidrólise da lactose reduziram tanto a qualidade dos pós (cor, temperatura de transição vítrea, higroscopicidade, etc..), quanto sua secabilidade (ocorrência de adesão, empedramento e maior gasto energético para evaporação da água). A adição dos compostos de alta massa molar apresentou efeito positivo sobre as propriedades físico-químicas e de secabilidade dos pós, sendo a maltodextrina, o composto mais eficiente.
The objective of this work is to develop a mathematical model that allows for thermodynamically evaluating of spray dryers through mass/energy balance, to elaborate products from mixing of the milk and whey and to evaluate the effect of compounds with high molecular weight in the physicochemical properties and drying characteristics of traditional and lactose-free dairy mixes. For the thermodynamic characterization, it has been utilized spray dryers with atomizer pressure nozzle (evaporation capacity: 1 kg of water/h) and with atomizer disc (evaporation capacity: 20 kg of water/h). For elaboration of the dairy mix, there have been used lactic bases (lactose containing and non-lactose containing bases), elaborated from different proportions of milk and whey, maltodextrin, inulin and soluble corn fiber. The mathematical model has been validated for the evaluation of mass and energy losses and allowed to compare the efficiency between spray dryers with different designs. The increase in whey content in dairy mix and, especially, the application of the lactose hydrolysis reduced both the quality of the powders (color, glass transition temperature, hygroscopy, etc) and drying properties (stickiness, caking and increased energy expenditure for water evaporation). The addition of the compounds with high molecular weight had a positive effect on the physicochemical properties and the drying of the powders, being maltodextrin the most efficient compound.

Le développement actuel des moteurs doit répondre à une volonté de réduction de la consommation et à des normes de plus en plus sévères. Les moteurs Diesel, bien que performants, présentent des émissions trop importantes d'oxydes d'azote (NOx) et de particules de suies. Ces émissions polluantes proviennent essentiellement de l'existence de zones riches en carburant ne permettant pas une combustion optimale. La préparation du mélange air / carburant, fortement conditionné par l'entraînement d'air par le spray est donc essentielle. La Vélocimétrie par Images de Particules sur traceurs Fluorescents, associée à un traitement spécifique des champs de vitesses instantanés de la phase gazeuse externe sont utilisés afin d'obtenir des mesures en proche frontière du spray. Dans la zone quasi statique du spray, un effet important de la densité ambiante sur le taux de mélange est mis en évidence. D'autre part, la diminution du diamètre de trou d'injecteur améliore sensiblement le taux de mélange local. Pour compléter cette analyse, un gain du taux de mélange entre les deux injecteurs est calculé pour chaque densité ambiante. Pour les fortes densités, le gain issu de la réduction du diamètre de trou peut at! teindre une valeur importante (> 60%). La phase gazeuse latérale dans la zone instationnaire du spray est ensuite investiguée et la méthodologie de la F-PIV est transposée à cette zone. Un lien entre la longueur de pénétration du spray et des longueurs d'entraînement est défini. La densité ambiante n'a pas d'effet sur ces longueurs d'entraînement. La diminution du diamètre de trou engendre une augmentation du gaz entraîné à une distance plus courte du nez de l'injecteur. Cependant, cette étude montre que les deux sprays n'engendrent pas un entraînement de gaz similaire
The actual development of the engine must reply to a will of fuel consumption reduction and to stricter norms concerning the pollutant emissions. Although the Diesel engines are competitive, the NOx and soot particle emissions mainly come from the existence of wealthy fuel zone preventing an optimal combustion. Therefore, the air / fuel mixing preparation, highly controlled by the air entrainment in spray, is essential. Particle Image Velocimetry on fluorescent tracers, associated with a specific processing of the instantaneous velocity fields have been applied to obtain measurements in the near vicinity of the spray edge. In the "quasi- teady" region of the spray, the important effect of the ambient density on the mixing rate has been pointed out. On the other hand, an orifice diameter decrease significantly improves the local air / fuel ratio. To complete this analyse, a gain in mixing rate between two different injectors has! been calculated for each gas density. For high densities, the gain due to a reduction of the hole diameter can reach important value (> 60%). Then, lateral gaseous phase in no stationary zone of spray is studying and F-PIV method is transposed to this zone. A link between the penetration length and entrainment lengths is defined. Ambient density has not effect on entrainment lengths. The hole diameter decrease generates entrained gas increase at shorter distance of injector nozzle. However, this study shows two sprays do not generated the same gas entrainment

An examination of parameters affecting the control of a jet vectoring technique used in the Coanda-assisted Spray Manipulation (CSM) is presented. The CSM makes use of an enhanced Coanda effect on axisymmetric geometries through the interaction of a high volume primary jet flowing through the center of a collar and a secondary high-momentum jet parallel to the first and adjacent to the convex collar. The control jet attaches to the convex wall and vectors according to known Coanda effect principles, entraining and vectoring the primary jet, resulting in controllable r-θ directional spraying. Several control slots (both annular and unique sizes) and expansion radii were tested over a range of momentum flux ratios to determine the effects of these variables on the vectored jet angle and profile. Two- and three-component Particle Image Velocimetry (PIV) was used to determine the vectoring angle and the profile of the primary jet in each experiment. The experiments show that the control slot and expansion radius, along with the momentum ratios of the two jets, predominantly affected the vectoring angle and profile of the primary jet. The Reynolds number range for the primary jet at the exit plane was between 20,000 and 80,000. The flow was in the incompressible Mach number range (Mach< 0.3).

Breathable water-repellent garments are common products on the outdoor market. There are many recommendations on how to wash and waterproof your garment in order to make sure that its water-repellence is cared for, but the advice given by different sources is inconsistent. Are expensive products really necessarily or are regular laundry products just as good? What waterproofing agents should one use in order to insure that the water-repellent layer is restored? Four different water-repellent wash-in products were tested on polyester and polyamide fabrics. Seven laundry products and two water-repellent wash-in products were tested on jackets with dendrimer based finishes and untreated polyamide fabrics. The results were evaluated by spray testing according to ISO EN 24920 and sessile drop tests. Not all wash-in products offer good water-repellence on polyamide and polyester fabrics. Two laundry detergents decreased the water-repellence of the jackets. The laundry detergents did not affect the function of wash-in waterproofing agents on the jackets. The water-repellence of one wash-in product was affected by the use of two different detergents on untreated fabric
Program: Textilingenjörsutbildningen

U okviru ove disertacije su ispitane mogućnosti primene savremenih postupaka za dobijanje ekstrakata rtanjskog čaja (Satureja montana L.).U ekstraktima dobijenim primenom superkritičnog ugljendioksida (različitih gustina) utvrđeno je prisustvo karvakrola kao najzastupljenije komponente. Ekstrakt sa najvećim sadržajem karvakrola je dobijen pri uslovima 350 bar i 50 °C (60,82%), dok je najveći prinos karvakrola ostvaren pri pritiscima 325 i 350 bar i temperaturi 60 °C, i iznosio je 2,4 g/100 g droge. Primenom ugljendioksida na većim pritiscima se ostvaruje efikasnija ekstrakcija karvakrola iz droge, kao i proizvodnja ekstrakata sa većim sadržajima karvakrola. Druge komponente prisutne u ekstraktima u znatno nižim koncentracijama su: p-cimen, borneol, trans-kariofilen, kariofilen-oksid, γ-terpinen i linalool.Da bi se utvrdila mogućnost unapređenja prinosa ekstrakcije superkritičnim ugljendioksidom, kao i poboljšanja kvaliteta ekstrakata, ispitan je uticaj različitih predtretmana biljnog materijala. Ustanovljeno je da predtretman vodom najznačajnije povećava prinos ekstrakcije (za 25%), dok je ultrazvučni predtretman najadekvatniji izbor za dobijanje ekstrakata sa najvećim sadržajem karvakrola (66,46%). Međutim, najveći prinos ekstrakcije karvakrola iz 100 g droge postignut je primenom etanola i vode kao predtretmana.Ekstrakti dobijeni primenom subkritične vode (uz variranje temperature i vremena ekstrakcije) su hemijski okarakterisani i radi utvrđivanja uslova ekstrakcije pri kojima se postiže najveći kvalitet ekstrakata u pogledu sadržaja polifenolnih komponenti, kao i antioksidantne aktivnosti, primenjena je metoda odzivne površine (RSM). Utvrđena je prednost primene subkritične vode u odnosu na klasičnu metodu ekstrakcije u pogledu sadržaja polifenolnih komponenti i antioksidantne aktivnosti.Suvi ekstrakti S. montana dobijeni spray drying tehnologijom sušenja (sa različitim koncentracijama maltodekstrina) su ispitani u pogledu fizičkih i hemijskih osobina. Takođe, radi ispitivanja mogućnosti primene u vidu funkcionalnih ili prehrambenih proizvoda, izvršena je senzorna analiza dobijenih suvih ekstrakata, i analizirana je njihova farmakološka aktivnost u smislu ACE inhibitornog i antioksidantnog delovanja.Ustanovljeno je da je najniža koncentracija maltodekstrina (10%) najadekvatnija za dobijanje suvog ekstrakta S. montana sa najvećim sadržajem polifenolnih komponenti, sadržajem etarskog ulja i u pogledu antioksidantne i ACE inhibitorne aktivnosti. Takođe, suvi ekstrakt sa 10% maltodekstrina ispunjava i ostale fizičko-hemijske parametre, kojima se osigurava kako efikasno sušenje, tako i kvalitet ekstrakta.In vivo aktivnost odabranih ekstrakata S. montana ispitana je na modelu hepatotoksičnosti indukovane primenom ugljentetrahlorida. Analiziran je uticaj ekstrakata na funkciju jetre, enzimske parametre oksidativnog stresa i serumske parametre oksidativnog oštećenja izazvanog ugljentetrahloridom i ustanovljen je hepatoprotektivni učinak ekstrakata S. montana. Takođe, ispitano je dejstvo ekstrakata na rast Ehrlich-ovih ascitnih tumora implantiranih miševima, kao i na biohemijske parametre oksidativnog stresa u ćelijama tumora i utvrđeno je da je vreme aplikacije ekstrakata od izuzetnog značaja.
This dissertation investigates the possibilities of applying contemporary processes for obtaining extracts of winter savory (Satureja montana L.).Carvacrol was determined to be the most abundant component in extracts acquired by using supercritical carbon dioxide (of various densities). Extract with the richest content of carvacrol was obtained under conditions of 350 bar and 50 °C (60,82%), while the highest carvacrol yield was produced under 325 bar and 350 bar pressures and at a 60 °C temperature reaching 2.4 g/100 g of dry weight. By applying carbon dioxide on higher pressures, a more efficient carvacrol extraction from herbal material is performed, alongside production of extracts with higher carvacrol content. Other components in the extracts present in significantly lower concentrations are the following: p-cymen, borneol, trans-caryophyllene, caryophyllene-oxide, γ-terpinene and linalool.In order to recognize the possibility of improving the extraction yield produced by employing supercritical carbon dioxide and enhancing the quality of extracts, the influence of several different pre-treatments was investigated. It was determined that the water pre-treatment raises the extraction yield the most (for 25%), while the ultrasonic pre-treatment was the most adequate choice for acquiring extracts with the highest content of carvacrol (66.46%). However, the highest carvacrol extraction yield from 100 g of dry weight was achieved by applying ethanol and water as pre-treatment.Extracts which were attained with subcritical water (by varying the temperature and time of extraction) were chemically characterized and Response Surface Method (RSM) was applied for the purposes of determining conditions of extractions under which the highest quality of extracts in terms of content of polyphenolic compounds and antioxidant activity is reached. The advantage of employing subcritical water over the classical method of extraction in respect of content of polyphenolic components and antioxidant activity was demonstrated.Dry extracts of S. montana obtained by using the spray drying technology (with different concentrations of maltodextrine) were examined in terms of their physical and chemical characteristics. Also, in order to investigate the possibility of their use as functional or food products, sensory analysis of attained extracts was performed, and furthermore, their pharmacological activity in terms of the ACE inhibitory and antioxidant effect was analysed as well.It was determined that the lowest concentration of maltodextrin (10%) was the most adequate for obtaining dry extracts of S. montana with the richest content of polyphenolic components and essential oil, and in respect of antioxidant and ACE inhibitory activities. Also, dry extract with 10% of maltodextrin meets all other physical-chemical parameters, which provide efficient drying and quality of extracts.In vivo activity of selected extracts of S. montana was examined on a model of hepatotoxicity induced by applying carbon tetrachloride. The influence of extracts on liver function, enzyme parameters of oxidative stress, and serum parameters of oxidative damage caused by carbon tetrachloride was analysed and hepatoprotective effect of S. montana extracts was determined. In addition, the influence of extracts on the growth of Ehrlich ascite tumors implanted in mice was investigated, and their impact on biochemical parameters of oxidative stress in tumor cells as well, and it was determined that the time of application of extracts is of great significance.

This thesis considers the effect of manufacturing conditions and polymer ratio on water permeability and morphology of free-films. A novel spray method for producing ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) free-films was developed where several process parameters was controlled. The process was optimised by pre-spraying solvent until the system reached a steady-state temperature. This minimised the variation of outlet air temperature to < 2.5 °C. Coating time was approximately 4 minutes excluding drying.

Free-films were produced using 94 wt% solvent (95 %-ethanol) and 6 wt% polymer. The amount of HPC in the films was varied (wt% HPC defined as HPC/(HPC+EC)*100). Films with 30-40-50-57 wt% HPC were studied. Phase diagrams was constructed to study the phase transformation of polymer mixtures. Results show that all polymer mixtures with HPC content above 30 wt% were phase separated prior to film manufacturing. Temperature had an effect on the polymer phase transformation. In the phase diagram, the 2-phase area was larger for temperatures above 40 °C.

The investigated manufacturing conditions were outlet air temperature (°C) and spray rate (g/min). Outlet air temperature was controlled by adjusting the inlet air temperature. The films were characterized by measuring water permeability (m²/s). Cross section structure of the films was analyzed with confocal laser scanning microscopy (CLSM). FITC-HPC was added for enhanced contrast between the domains.

Higher outlet air temperature gave higher water permeability of the film whereas higher spray rate gave lower water permeability. The outlet air temperature had an impact on evaporation rate. The evaporation rate together with spray rate affected the solidification and hence the structure of the film. Images show that longer solidification time smeared the domains into larger domains. Lower water permeability was caused by less connectivity between the pores.

In conclusion, experiments show that water permeability of EC/HPC free-films was highly dependent on the manufacturing conditions.

 

The objective of this research is to further define the relationship between the charge state of insulin, and the self assembly properties of insulin and PEGylated insulin in solution. Polyethylene glycol (PEG) chains were covalently attached to insulin in order to evaluate their impact on insulin's systemic duration of action after pulmonary dosing. This thesis will focus on the assembly properties of the PEG-insulin and insulin, and also demonstrate how the charge state, which was modified by the covalent attachment of PEG, relates to different modes of behavior by anion and cation exchange chromatography. In addition, explain how modifying the assembly state extends to improving formulation properties of spray-dried insulin powders. This thesis is an investigation into the relationship of insulin's charge state controlled by pH and how the charge state affects the self assembly of insulin, especially when the zinc ion is removed. Ionic interaction is one of the major forces affecting insulin assembly. The theory that a change in the charge state of insulin could modulate the ionic interaction and reduce hexamer formation at alkaline conditions was investigated. Experiments were designed to measure the level of hexamer with light scattering, and the amount of hexamer was then correlated with the pH and zinc content of the solutions. The importance of the charge state of the monomer and its behavior extends to chromatography and purification modes as well. Specifically, the purification of various species of PEGylated insulin presents a challenge. By varying mobile phase pH which induces the charge to insulin, an ion exchange method demonstrated very high resolution and controllable interaction between the ion exchange media and the insulin derivatives. A highly accurate method for determining molecular weight and thus the average associated state of insulin in solution has been developed using the MALS (Multi-Angle Light Scattering). Insulin concentration, pH, and metal ion concentrations, were in pharmaceutically relevant ranges. The MALS method was developed to evaluate how the parameters above affect the self-assembly properties of insulin, and use the assembly properties to improve formulations of insulin or PEGylated insulin. To use the light scattering technique the dn/dc (change in refractive index with change in concentration) is required. During the method development, the dn/dc of insulin was measured at 690 nm, and a value of 0.185 mL/g based on theory was confirmed. A novel approach for preparing insulin powders with improved chemical stability, based on maintaining the dissociation of hexamers in solution during the spray drying process was developed. The mode presented here is to remove the zinc ions from solution, increase the pH from 6.6 to 7.8, and maintain a low concentration of insulin approximately 2 to 15 mg/mL. Each of these factors alone decreases the hexamer population in solution, but by combining all three factors, hexamers are driven to very low levels of equilibrium. The increased stability of the powders is predominately related to the decrease in covalent insulin dimer (CID). The data presented correlates a reduced hexamer population in the solution with lower levels of CID's in the dry powder compared to controls. The CID formation rate was reduced by 40% compared to a control.

Le phénomène de dérive constitue un enjeu environnemental et sanitaire majeur lors de la pulvérisation de solutions phytosanitaires sur les surfaces agricoles. Sous l'action du vent, des gouttelettes peuvent dériver loin des champs ciblés et être source de pollution. Une stratégie pour limiter la dérive est de contrôler la distribution de taille des gouttes de spray, en réduisant la proportion de petites gouttes. Dans ce but, des additifs anti-dérives, tels que des émulsions diluées d'huile dans l'eau, ont été développés. Bien que largement étudiés, les effets de ces émulsions ne sont pas encore bien compris. L'objectif de cette thèse est d'élucider les mécanismes à l'origine de l'augmentation de la taille des gouttes de spray à base d'émulsions.La pulvérisation implique la fragmentation d'un flux de liquide par une buse hydraulique. A la sortie de la buse, une nappe libre de liquide est formée, puis déstabilisée en gouttes. Afin d'élucider les mécanismes à l'origine des effets anti-dérives des émulsions, nous étudions l'influence de ces émulsions sur les mécanismes de déstabilisation des nappes liquides. Une expérience modèle basée sur la collision d'une goutte de solution sur une cible solide est utilisée pour produire et visualiser des nappes liquides. Lors de l'impact, la goutte s'aplatit en une nappe qui s'étend radialement dans l'air, bordée par un bourrelet plus épais. Différents mécanismes de déstabilisation sont observés en fonction des propriétés des fluides. Une nappe d'eau pure s'étale radialement puis se rétracte par effet de la tension de surface ; simultanément, le bourrelet est déstabilisé en gouttes. Pour une émulsion diluée d'huile dans l'eau, le mécanisme de déstabilisation dominant est considérablement modifié: les nappes sont déstabilisées par la nucléation de trous qui perforent le film liquide lors de son expansion; les trous grandissent jusqu'à la formation d'un réseau de ligaments, qui est ensuite déstabilisé en gouttes.Une étude systématique de l'influence des paramètres physico-chimiques de l'émulsion, tels que la concentration en huile et la distribution de taille de gouttelettes d'huile, sur le mécanisme de perforation est conduite. Nous établissons une corrélation entre le nombre d'évènements de perforations observés dans les nappes modèles et la distribution de taille de gouttes de sprays formés avec des buses de pulvérisation agricoles. Ce résultat démontre la pertinence expérimentale de notre expérience modèle pour comprendre les mécanismes d'actions des formulations anti-dérives. Nous montrons ainsi que le mécanisme à l'origine de l'augmentation de la taille des gouttes de spray à base d'émulsion est un mécanisme de perforation.Pour comprendre les mécanismes à l'origine de la perforation, nous développons une technique optique permettant de mesurer le champ d'épaisseur de nappes liquides. Nous constatons que la formation d'un trou dans la nappe est systématiquement précédée par un amincissement local du film liquide. Nous montrons que cet amincissement est le résultat de l'entrée puis de l'étalement par effet Marangoni de gouttelettes d'huile à l'interface air/eau. L'amincissement du film liquide conduit in fine à sa rupture.Nous proposons un mécanisme de perforation en deux étapes: les gouttelettes d'huile (i) entrent à l'interface air/eau, et (ii) s'étalent à l'interface. La formulation de l'émulsion est un paramètre critique pour contrôler le processus de perforation. L'addition de sels ou de copolymères amphiphiles à des émulsions stabilisées par des tensio-actifs ioniques peut soit déclencher, soit inhiber le mécanisme de perforation. Nous montrons que l'entrée de gouttes d'huile à l'interface air/eau est l'étape limitante de ce mécanisme. Les interactions répulsives de nature stérique et/ou électrostatique entre les gouttelettes d'huile et l'interface stabilisent le film liquide, empêchant les gouttelettes d'entrer à l'interface, et ainsi inhibent le processus de perforation
One of the major environmental issues related to spraying of pesticides on cultivated crops is the drift phenomenon. Because of the wind, small droplets may drift away from the targeted crop and cause contamination. One way to reduce the drift is to control the spray drop size distribution and reduce the proportion of small drops. In this context, anti-drift additives have been developed, including dilute oil-in-water emulsions. Although being documented, the effects of oil-in-water emulsions on spray drop size distribution are not yet understood. The objective of this thesis is to determine the mechanisms at the origin of the changes of the spray drop size distribution for emulsion-based sprays.Agricultural spraying involves atomizing a liquid stream through a hydraulic nozzle. At the exit of the nozzle, a free liquid sheet is formed, which is subsequently destabilized into droplets. In order to elucidate the mechanisms causing the changes of the spray drop size distribution, we investigate the influence of emulsions on the destabilization mechanisms of liquid sheets. Model single-tear experiments based on the collision of one tear of liquid on a small solid target are used to produce and visualize liquid sheets with a fast camera. Upon impact, the tear flattens into a sheet radially expanding in the air bounded by a thicker rim. Different destabilization mechanisms of the sheet are observed depending on the fluid properties. A pure water sheet spreads out radially and then retracts due to the effect of surface tension. Simultaneously, the rim corrugates forming radial ligaments, which are subsequently destabilized into droplets. The destabilization mechanism is drastically modified when a dilute oil-in-water emulsion is used. Emulsion-based liquid sheets are destabilized through the nucleation of holes within the sheet that perforate the sheet during its expansion. The holes grow until they merge together and form a web of ligaments, which are then destabilized into drops.The physical-chemical parameters of the emulsion, such as emulsion concentration and emulsion droplet size distribution, are modified to rationalize their influence on the perforation mechanism. We correlate the size distribution of drops issued from conventional agricultural spray with the amount of perforation events in single-tear experiments, demonstrating that the single-tear experiment is an appropriate model experiment to investigate the physical mechanisms governing the spray drop size distribution of anti-drift formulations. We show that the relevant mechanism causing the increase of drops size in the emulsion-based spray is a perforation mechanism.To gain an understanding of the physical mechanisms at the origin of the perforation events, we develop an optical technique that allows the determination of the time and space-resolved thickness of the sheet. We find that the formation of a hole in the sheet is systematically preceded by a localized thinning of the liquid film. We show that the thinning results from the entering and Marangoni-driven spreading of emulsion oil droplet at the air/water interface. The localized thinning of the liquid film ultimately leads to the rupture of the film. We propose the perforation mechanism as a sequence of two necessary steps: the emulsion oil droplets (i) enter the air/water interface, and (ii) spread at the interface. We show that the formulation of the emulsion is a critical parameter to control the perforation. The addition of salt or amphiphilic copolymers can trigger or completely inhibit the perforation mechanism. We show that the entering of oil droplets at the air/water interface is the limiting step of the mechanism. Thin-film forces such as electrostatic or steric repulsion forces stabilize the thin film formed between the interface and the approaching oil droplets preventing the entering of oil droplets at the interface and so inhibit the perforation process

This thesis deals with reaction synthesis of materials Fe–Al, Fe–Cu and Fe–Ni from cold spray. In literature analysis are introduced these systems and for each system there is brief description of binary equilibrium diagram. Furthermore here are some short explanations of diffusion, Kirkendall effect and other possible processing technologies of intermetallic materials. In experimental part, samples of sprayed materials were annealed and then microstructural changes were investigated. This thesis contains photographs of microstructure, results from scanning electron microscopy, X-ray, and measurements of microhardness.

This work deals with issues of preparation of intermetallics based on iron, nickel and titanium aluminides. It works with an idea of preparation of bulk material by reaction synthe-sis from kinetic spraying deposits by cold spray. Theoretical part is concerned with phases and compounds of these aluminides for structural applications, their characteristics and present fabrication. In experimental part there are studied microstructures created by annealing of deposits.

L'objectif de cette thèse est la préparation d’aérogels biosourcés ayant des propriétés de super-isolation thermique. Pour cela, nous avons choisi de développer de nouveaux aérogels à base de nanofibres de cellulose (NFC). Les aérogels ont été préparés par lyophilisation. Dans un premier temps, une analyse des paramètres expérimentaux jouant un rôle sur la morphologie et les propriétés physico-chimiques des aérogels a été réalisée afin d’obtenir les meilleures propriétés d’isolation thermique. Avec une suspension de NFC à 2% en masse, sans ajout de sels et sans faire varier le pH, une lyophilisation réalisée dans des moules d’aluminium à une température de -80°C a permis d’obtenir des aérogels ayant une conductivité thermique de 0,024 W/m.K. Afin de diminuer cette conductivité thermique, nous avons choisi de réduire la taille des pores pour obtenir un effet Knudsen. Pour cela, une nouvelle technique de séchage a été proposée : la lyophilisation par pulvérisation. Les aérogels préparés dans les mêmes conditions expérimentales que précédemment avec cette technique ont des propriétés thermiques super-isolantes (0,018 W/m.K) grâce à la nano-structuration du réseau poreux. Finalement, un nouveau dispositif expérimental a été développé pour caractériser plus finement les propriétés thermiques des aérogels. C’est un dispositif transitoire impulsionnel qui permet d'estimer simultanément la contribution de la conduction solide et gazeuse, l'effet radiatif et la diffusivité thermique grâce à un modèle théorique simple. Ce dispositif permettra d’approfondir l’étude complexe du transfert thermique à travers des matériaux poreux semi-transparents tels que les aérogels
The objective of this thesis is the preparation of renewable aerogels having thermal super-insulating properties. To do it, we designed new aerogels from nanofibrillated cellulose (NFC) by freeze-drying. This technique is simple and has the advantage of not using organic solvents. First of all, the parameters playing a role on the aerogel morphology and physico-chemical properties of the aerogels were analyzed to get the best thermal insulating properties. Using 2 wt% NFC suspensions, without addition of salts, keeping the initial pH, the obtained freeze-dried aerogels in alumina molds at -80 °C have a thermal conductivity of 0.024 W/m.K. In order to reduce the pore size and to improve the thermal insulating properties by Knudsen effect, a new drying technique was proposed: the spray freeze-drying. Aerogels prepared in the same experimental conditions with this technique have thermal super-insulating properties (0.018 W/m.K) thanks to the nanostructuration of the porous network. Finally, a new device was designed to characterize more precisely the thermal properties of aerogels. This is an impulsive transient device, which can estimate simultaneously the contribution of solid and gas conduction, the radiative effect and thermal diffusivity using a simple theoretical model. This device will allow studying complex heat transfer through porous semi-transparent materials such as aerogels

Dans la perspective d’améliorer les cellules du futur, nous avons élaboré respectivement des couches minces de ZnO dopé Mo par la méthode spray pyrolyse et dopé Yb par sputtering. Quel que soit la technique utilisée, toutes ces couches sont polycristallines, transparentes avec des surfaces uniformes. De plus les mesures d’effet Hall montrent une conductivité de type n dans le cas des deux systèmes étudiés. Concernant les films minces de ZnO dopé Mo, les propriétés électriques restent potentiellement intéressantes pour des applications en photovoltaïque en tant que dopant additionnel en plus des terres rares. Quant aux films minces de ZnOYb, les résultats de mesures PL ont clairement mis en évidence un couplage optique entre ZnO et l’Yb avec l’observation d’un photon infrarouge pour un photon UV incident. Ceci suggère que le concept « down-shift » est susceptible d’être validé
In view of improving the cells of the future, we have elaborated respectively doped ZnO thin films by Mo spray pyrolysis method and doped Yb by sputtering. Whatever the technique used all these layers are polycrystalline, transparent with smooth surfaces. In addition, the Hall effect measurements show an n-type conductivity in the case of two systems studied. On thin films of ZnO doped Mo, the electrical properties are potentially interesting for photovoltaic applications as additional dopant in addition to rare earths. As for thin films ZnOYb, PL measurement results have clearly demonstrated an optical coupling between ZnO and Yb with the observation of a photon infrared photon UV incident. This suggests that the concept of "down-shift" is likely to be validated

Dans la présente étude, la conductivité thermique et le module d'élasticité de revêtementsd’YPSZ élaborés par projection plasma ont été prédits par modélisations numériques 2D et3D de type différences finies et éléments finis.L'influence de la résolution d'image, de la taille et de la valeur du seuil sur les propriétésprédites du revêtement a été étudiée. En outre, les effets de la méthode numérique et du typede condition aux limites ont été étudiés. En particulier, la quantification de l'effet Knudsen(effet de raréfaction) sur le transfert de chaleur à travers une structure poreuse a été réaliséepar modélisation numérique en combinaison avec l'analyse d'image. Les conductivitéseffectives obtenues par modélisation 3D s'avèrent plus élevées que celles obtenues en 2D, etaussi en meilleur accord avec les résultats mesurés. Une corrélation 2D/3D a été trouvéepour la modélisation de la conductivité thermique : cette corrélation permet de prédire lesvaleurs 3D à partir des valeurs calculées en 2D
In the present study, the thermal conductivity and elastic modulus of thermal spray YPSZcoatings were predicted by 2D and 3D finite differences and finite elements numericalmodeling based on cross-sectional images.The influence of the image resolution, size and threshold on the predicted properties of thecoating was studied. Moreover, the effects of the numerical method and of the boundarycondition were investigated. In particular, the quantification of the Knudsen effect(rarefaction effect) on the heat transfer through a porous structure was realized by numericalmodeling in combination with image analysis. The predicted thermal conductivities obtainedby 3D modeling were found to be higher than those obtained by 2D modeling, and in betteragreement with the measured results. A 2D/3D correlation was sucessfully found for themodeling of thermal conductivity: this correlation allows predicting 3D computed valuesfrom 2D ones